SAN FRANCISCO (AP) - Oracle Corp. has hired former Hewlett-Packard Co. CEO Mark Hurd to help lead the database software maker in a pivotal moment in its 33-year history as it tries to muscle in on more of HP’s turf.

Oracle and HP are longtime partners, but Hurd’s appointment Monday as co-president of Oracle underscores the growing fissure between the Silicon Valley heavyweights, and Oracle CEO Larry Ellison’s belief that his friend Hurd was railroaded out of a job at HP.

With Hurd climbing aboard Oracle, one of the company’s current co-presidents, Charles Phillips, a former Marine and investment banker who was with Oracle for seven years, is disembarking. Ellison said that Phillips wanted to leave in December, but that Ellison asked him to stay through the integration of Sun Microsystems.

Phillips was in the news earlier this year when pictures of him snuggling with his former mistress appeared on billboards around the U.S. Ellison said Oracle will miss Phillips’ talent and leadership but that he respects Phillips’ decision to leave.

Oracle said in a statement that Hurd will also serve as a member of the board of directors. He will report to Ellison.

In the statement, Ellison praised Hurd’s tenure at HP and said no other executive had more relevant experience.

“Mark did a brilliant job at HP and I expect he’ll do even better at Oracle,” Ellison said. “There is no executive in the IT world with more relevant experience than Mark. Oracle’s future is engineering complete and integrated hardware and software systems for the enterprise.”

Hurd is being tapped as Oracle undergoes a similar transformation to the one he spearheaded in his five years atop HP.

Oracle is in a richly profitable business as the No. 1 seller of database software, but is trying to carve out territory in other areas.

Oracle has been on a $40 billion buying binge since 2004, scooping up companies in other parts of the business software market, and with the $7.4 billion deal for Sun last year, Oracle became a direct competitor to HP in computing hardware _ specifically, the computer servers that power businesses’ back offices.

Hurd presided over a similarly massive makeover at HP, where he engineered more than $20 billion in acquisitions. Those deals helped HP become less tethered to printer ink as the source of the bulk of its profits. HP is now a player in technology services _ where it’s battling IBM Corp. _ and computer networking _ where it’s taking on Cisco Systems Inc., which is also now making its own servers and challenging HP in that market.

Hurd is known as an extreme cost-cutter. HP announced about 50,000 job cuts during his tenure.

Hurd resigned a month ago from HP following a sexual harassment investigation. The investigation unearthed inaccurate expense reports connected with Hurd’s outings with his eventual accuser, an actress and HP contractor named Jodie Fisher.

She claimed that her work helping organize HP events dried up after she rebuffed Hurd’s advances.

Hurd, 53, who is married with two children, denies making any advances on Fisher. Hurd also insists he didn’t prepare his own expenses and didn’t try to conceal his outings with Fisher, which often included dinner after the events Fisher helped organize and that Hurd attended.

He called HP’s decision to oust Hurd the worst personnel decision since Apple Inc. forced out Steve Jobs _ another of Ellison’s friends _ 25 years ago. Ellison said the HP board’s decision to publicly disclose the harassment claim against Hurd amounted to “cowardly corporate political correctness,” as the board had found that Hurd didn’t violate the company’s sexual harassment policies.

HP has emphasized that its board voted unanimously for Hurd’s resignation.